The present invention relates to a lance for blowing an oxidizing gas, especially oxygen, onto a bath of molten metal in a crucible for metalurgically treating the molten metal, especially for refining pig iron into steel.
More precisely, the invention relates to a blowing lance, the nose of which comprises in addition to the usual main apertures opening at the front face of the tip of the the lance and serving to blow oxygen in form of jets of great impulsion for the refining of the metal (oxidation of impurities of the metal bath), a plurality of auxiliary apertures for blowing oxygen streams of lesser speed onto the bath in order to improve the rate of secondary combustion of the refining gas.
The "nose" of the lance constitutes its end through which the refining gas passes toward the bath of metal. Generally, the "nose" is a piece of curved copper connected to the end of the lance.
The "front face" is the part of the nose which is directed toward the metalic bath contained in the crucible.
It is also mentioned that the rate of the secondary combustion is expressed in the proportion of CO.sub.2 in the reaction gas, which CO.sub.2 is obtained by the oxydation of CO which emanates from the metalic bath following the decarburization of the latter by the oxygen refining.
Multivallent lances of this type already exist. However, improvement of these lances is still possible, especially with respect to increase the secondary combustion of the gas of the reaction, as well as to improve the durability of the nose of the lance.